examples: take lines out of loop (refactor)

since they will only be executed once.

Also, an error is raised if a connection is not found

examples/python/gi/update-ip4-method.py

@@ -42,16 +42,16 @@ if __name__ == "__main__":
     # create Client object
     client = NM.Client.new(None)
 
-    all_connections = client.get_connections()
+    try:
-    for c in all_connections:
+        conn = next(c for c in client.get_connections() if c.get_uuid() == uuid)
-        if c.get_uuid() != uuid:
+    except StopIteration:
-            continue
+        sys.exit("not found connection with uuid=%s" % uuid)
 
     # add IPv4 setting if it doesn't yet exist
-        s_ip4 = c.get_setting_ip4_config()
+    s_ip4 = conn.get_setting_ip4_config()
     if not s_ip4:
         s_ip4 = NM.SettingIP4Config.new()
-            c.add_setting(s_ip4)
+        conn.add_setting(s_ip4)
 
     # set the method and change properties
     s_ip4.set_property(NM.SETTING_IP_CONFIG_METHOD, method)
@@ -67,8 +67,7 @@ if __name__ == "__main__":
             s_ip4.props.gateway = sys.argv[5]
 
     try:
-            c.commit_changes(True, None)
+        conn.commit_changes(True, None)
         print("The connection profile has been updated.")
     except Exception as e:
         sys.stderr.write("Error: %s\n" % e)
-        break